5.1 96/24 Audio Downloads?

iTunes is proving every day that some music fans love to procure music through the Internet. On the other hand, audiophiles often complain about the poor sound of the "CD quality" compressed files that Apple and others offer for download at similar prices to those of their uncompressed CD counterparts.

But audiophiles can still be optimistic about downloading if they observe that, bandwidth issues aside, there is no technical reason why the audio resolution offered by online music services needs to remain low-rez. The AAC codec used by Apple, Real Audio's codecs, and Microsoft's WMA platform can all accommodate high-resolution audio as the market demand inevitably develops—something that Microsoft demonstrated to us at the January 2004 CES in Las Vegas.

DTS is also getting ready to join the high-rez download party when it begins within the next few years. The company is reporting that it has demonstrated the viability of streaming high-definition surround-sound audio over the Internet in a recent trial with Swedish Radio (SR). DTS says that audio mixed live in 5.1-channel surround sound from an outside broadcast was encoded at 24 bits/96kHz using the company's Coherent Acoustics codec, and streamed onto the Sprint Network via Internet protocol at 1.5Mbs.

We've reported in the past how SR has experimented with high-rez audio over the air using a Sirius digital radio satellite, but the recent event marked the first time that DTS Digital Surround has been streamed over an IP network. The company says the test "proves that high–bit-rate, high-quality surround-sound audio can now be streamed using DTS, providing a common delivery format for DVD, DVB, and digital cinema."

DTS' Ted Laverty notes that the exercise "arose out of our on-going cooperation with Swedish Radio and their continuing DTS-encoded DVB satellite service. They are experiencing a fast-growing demand for the high quality DTS downloads on their web site and were keen to examine the viability of providing a streaming signal of the same quality."

According to DTS, the signal feed for the test came from a live concert encoded with a DVB MPEG2 encoder with IP outputs. The signal was streamed using Internet protocol live onto the Sprint Network, and the signal was successfully recovered using a proprietary DTS software player the company says was designed for the purpose.

"The success of the test proves the viability of very high quality audio multicasting over broadband," claims DTS, "and points to the evolving potential for IP delivery of digital programming by broadcasters, particularly in Europe, where services offering up to 8Mbs connections are starting to come online."